The present invention relates to scanned imaging; and more particularly, it relates to devices for scanning a field to be imaged, such as a Tandem Scanning Microscope (TSM).
Image formation can be accomplished by confocal imaging techniques which involve mechanical or electronic scanning. Exemplary of these techniques is the Tandem Scanning Reflected Light Microscope (TSRLM). The theory of TSRLM is discussed by Petran and Hadravsky in "Tandem-Scanning Reflected-Light Microscope," Journal of the Optical Society of America, Vol. 58, No. 5, pp. 661-64 (May 1968). The TSRLM is further described and illustrated by Petran, Hadravsky, and Boyde in "The Tandem Scanning Reflected Light Microscope," SCANNING, Vol. 7, No. 2, pp. 97-108 (1985). U.S. Pat. No. 3,517,980 to Petran et al. also describes a TSRLM device.
The scanning device in a TSRLM is a rotating disk having holes in an annular region. The holes are arranged on Archimedean spirals. Diametrically opposite holes are on identical radii, and the pattern as a whole has a central symmetry. This device is known as a Nipkow disk. The structure of such a disk has conventionally been a copper foil sheet stretched over a retaining ring and having holes etched therein.